1. Field of the Invention
The invention relates, in general, to an instrument for the recording of data of physical magnitudes of an individual target. The invention includes a sensor, a data counter or comparator, fed by data pulses, an electric mean value calculator connected to an output of the counter and an electrical display which is also connected to the output of the counter. The physical magnitude of the target may, for instance, be a temperature, a pressure, a volume, a velocity or a weight of an individual target. The value of one of these physical magnitudes of the predetermined individual target is measured and recorded in accordance with the apparatus and associated method of the present invention.
2. Description of the Prior Art
The problems encountered in the determination of the data relating to a physical magnitude of an individual target over a period of time (at least one measuring period) and the identification of significant changes of the physical magnitude during one measuring period are explained below, with particular reference to the recording of individual body temperature data for a determination of the ovulation time of animals.
One method of determining the ovulation time of animals is based on the finding that hormonal changes in the female body lead to minute, but characteristic, temperature variations during the menstrual cycle. It is, in this case, important to determine the correct temperature rise which takes place within 48 hours, or less, following which the temperature on three following days is at least 0.2.degree. C., or possibly 2.0.degree. C., higher than on the preceding six days. In other words, it is important to determine the correct temperature rise during the 48 hours, or less, period which is immediately prior to the three day period in which the temperature is 0.2.degree. C., or possibly 2.0.degree. C., higher than on the preceding six days. It may be during these periods that the ovulation time occurs. The recording of this temperature rise is difficult, inter alia, because it depends on the individual characteristics of the individual bodies which may vary, for reasons including the general state of the health and the age of the animal.
A prior art electronic clinical thermometer provides a display of body temperature relative to a predetermined normal temperature. This device, however, has the disadvantage that the measured result drifts, since it changes as a function of time, while such change is not based on a temperature change of the body. The display shown might, in addition, disadvantageously include other physiologic data regarding the body which is measured. This drift, which is a long-term drift, is particularly pronounced when less complicated temperature sensors, such as NTC resistors, are employed. While deficiencies, or problems, may be reduced by the use of more sophisticated temperature sensors and evaluation electronics having a higher long-term stability, in order to be able to safely record the temperature difference of the body of about 0.2.degree. C., or possibly 2.0.degree. C., which is typical at the temperature rise, these highly stable temperature sensors and evaluation electronics, nevertheless, are very costly. Such cost adversely affects the wider use of ovulation time determination by electrical recording of body temperature deviation.
U.S. Pat. No. 4,396,020 discloses apparatus for the evaluation of the recorded body temperature data, for base temperature measurement. However, the disclosed apparatus does not provide for the technical recording to body temperature data, but rather, provides for the subsequent evaluation of this data by means of an algorithm based on medical knowledge.
In particular, temperature data pulses are counted in a data counter which adjusts a self-balancing bridge which acts as a data transformer. In one of the arms of the bridge, a thermistor is provided as a temperature sensor. The counter temperature data pulses are stored in another counter, after a temperature correction is made which is dependent on the measuring time. From the individual body temperatures stored on consecutive days, the mean value of these temperatures recorded during the course of eight days are calculated by a mean value calculator. The subsequently recorded individual body temperatures are compared with the mean value and the comparison result is accumulated and evaluated by an algorithm which determines the fertile and infertile days of the animal. Processing of the temperature data pulses, including mean value calculation, is complicated since relatively large amounts of data are evaluated. The data counter yields the data of the absolute body temperature. The absolute body temperature is also made the base, in at least the case of the correction made for measuring time, for the 8 day storage, for mean value calculation and comparison.
German Laid Open Patent No. 36 39 558 discloses an instrument for measuring temperatures wherein certain offset voltage variations of an operational amplifier are compensated. The input terminals of the operational amplifier are connected to a bridge circuit in which a temperature dependent resistor is provided as a sensor. Compensation is, essentially, obtained by a controlled switch which periodically applies a reference potential, instead of the output of a bridge, to the input terminals. Between the two input terminals, no external voltage exists so the operational amplifier provides the amplified offset voltage at its output terminals. The voltage can be stored and deducted from a sum voltage of a bridge voltage and an offset voltage normally occurring at the amplifier output. With this device, however, drifting of the sensor is not compensated and further processing of the temperature data is not simplified.
In German Laid Open Patent Application No. 36 39 557, a device is disclosed for the determination of the base temperature. The temperature rise which occurs in the middle of the cycle is recorded and the probable ovulation day determined, even in case of disturbed temperature values of the body. Particular measures concerning the problems of measuring techniques, such as to exactly record temperature data and to simplify the processing of the temperature data, are not provided.
German Laid Open Patent Application No. 33 42 251 discloses a method for measuring body temperature for the determination of the time of ovulation of an animal and calculates, at least over a part of a cycle of each day, a temperature curve which is recorded in short distances and stored. The stored temperature curve is evaluated to determine characteristic values while eliminating incidental variation. This principle is not employed in the present invention since it does not correct problems of exact recording of suitable temperature data. The evaluation of the temperature data in that case requires a particularly large amount of data. With a view to the amount of relatively long-drawn measurements, that method is hardly practical.
U.S. Pat. No. 4,031,365 discloses a system wherein body temperatures are recorded and evaluated as absolute body temperatures. This system yields a large amount of data which must be processed. In particular, the temperature values are stored in a four bit shift register from which a mean value is calculated. Subsequently, the mean value is compared, after digital-analog transformation, with an actual analog absolute temperature value in order to trigger an alarm signal when the value exceeds a predetermined temperature difference. If the absolute temperature values lie within the predetermined limits, they are continuously stored in the shift register in which the absolute temperature mean value is calculated.